Myocardial Ischemia is a disorder that usually is caused by a critical coronary artery obstruction, which is also known as atherosclerotic coronary artery disease (CAD). While diagnosis of myocardial ischemia prior to a heart attack is very beneficial, diagnosis is often problematic. The most conclusive diagnosis relies on imaging (e.g., nuclear myocardial scan, positron emission tomography (PET) scan, computed tomography (CT) scan, etc.) of the patient's coronary artery to visually detect obstructions. However, this is a costly and time-consuming procedure, and frequently no symptoms present themselves prior to the patient having a heart attack.
Other methods of detection involve monitoring and review of electrocardiography signals associated with the patient. Typically, these techniques monitor the electrocardiogram (ECG) signals, and in particular the characteristic shape of each cardiac cycle, which includes P, Q, R, S and T inflection points corresponding with underlying cardiac events. The presence of myocardial ischemia alters the conduction path of the depolarization wavefront, which is reflected in the monitored ECG waveform. For example, a partially blocked coronary artery may result in depression of the ST segment of the ECG waveform. A completely blocked coronary artery may result in elevation of the S-T segment of the ECG waveform. While less invasive than imaging techniques, myocardial ischemia does not always present with depressed or elevated ST segments, and therefore may fail to detect all obstructions.
It would therefore be desirable to provide a system and method of detecting electrocardiographic abnormalities indicative of myocardial ischemia that remains non-invasive.